1. Field of the Invention
The present invention relates to a piezoelectric/electrostrictive film, a method for producing the same, a piezoelectric/electrostrictive film type device, and a method manufacturing the same.
2. Description of the Related Art
In piezoelectric/electrostrictive film devices, it is usually necessary to fire device materials at a high temperature of 1000° C. or more and thus necessary to use materials resistant to the film formation temperature as substrates on which a lower electrode and a device are integrated. Therefore, the materials are limited to ceramic substrates difficult to finely process and electrode materials such as expensive platinum.
Therefore, in order to improve the degree of freedom of the selection of a substrate material and the like, various investigations have been made. For example, attempts have been made to decrease the firing temperature of a piezoelectric/electrostrictive film and bond a piezoelectric/electrostrictive self-supported film, which has been previously fired at a high temperature, to a substrate. There has also been the attempt of a method in which a piezoelectric/electrostrictive film is formed in an adherent state on a sapphire substrate in a high temperature process and bonded in an adherent state to a glass substrate or the like, and then the sapphire substrate is separated by laser destruction of the interface between the piezoelectric/electrostrictive film and the sapphire substrate (Japanese Unexamined Patent Application Publication No. 2004-260176).
However, piezoelectric/electrostrictive films having satisfactory characteristics in low-temperature firing have not been obtained, and piezoelectric/electrostrictive self-supported films have difficulty in the patterning necessary for devices from the viewpoint of the problem of strength and handleability of the films. In addition, the method using a sapphire substrate has the problem of the need for laser treatment and the problem of decreasing characteristics due to the formation of a destructed phase by laser irradiation. Thus, in the present situation, there have not been found methods for producing a piezoelectric/electrostrictive film and a piezoelectric/electrostrictive film device which satisfy the degree of freedom of the selection of a substrate material, productivity, and the characteristics of a piezoelectric/electrostrictive film device.